Health officials are investigating after 47 birds fell from the sky in Boston's Dorchester neighborhood on Thursday.

Rescuers were able to save 35 of the birds, but 12 have died. Investigators are working to determine the cause, and whether the deaths of two cats in the neighborhood could be related. A third cat was also affected.

"When I arrived, birds would fly, like from a house to a tree, they would flop in the tree and they would fall to the ground," said Alan Borgal of the Animal Rescue League of Boston. "The weaker ones were just falling right out the sky."

All the birds were grackles, black songbirds that typically travel in large flocks. They were found thrashing around on Bakersfield Street and the sidewalks nearby around 2 p.m.

"They could have put something out that was unintentional," said Meaney. "Something that didn't get along with this species of bird because we have two species here, and the other species did not die or get harmed."